Question

Briefly describe photorespiration. How does this differ from the normal function of the Calvin Cycle?

Answer 1

Photorespiration

Photorespiration can be defined as the evolution of CO2 during photosynthesis. It arises because rubisco can act as either a carboxylase or as an oxygenase.

When the oxygen levels are high, rubisco acts as an oxygenase and incorporate O2 into five carbon compound that is:-

RuBP(5-carbon)+O2?PGA(3-carbon)+glycolate(2-carbon)

factor that reduces the availability of CO2 or increases the availability of O2 to rubisco will increase the levels of photorespiration.

- Photorespiration differs from the Calvin cycle in that oxygen is consumed and carbon dioxide is released.